How will that create a seed stitch border? Are the instructions a misprint, possibly?

I don't think it will give you seed st. To get seed st on an EVEN number of sts: Row 1 = *k1, p1, rep* to end, Row 2 = *p1, k1 rep* to end. If you *k1, p1, rep * to end on the second row also, you'll get fisherman's rib.

If you are using and ODD number of sts, that's when you *k1, p1, rep* to end on all rows to get seed st.